AD 96-09-04

This amendment supersedes Airworthiness Directive (AD) 90-12-08, which currently requires the following on de Havilland Model DHC-3 airplanes: repetitively inspecting (using dye penetrant methods) the tailplane main rib forward flanges and the main rib forward lower flanges at the tailplane front attachment fitting for cracks and repairing any cracked flange. This AD action will retain the repetitive inspections currently required by AD 90-12-08, and will allow a certain modification as terminating action for these repetitive inspections. This action is prompted by the Federal Aviation Administration's determination that installing new angles and plates on the tailplane root ribs on de Havilland Model DHC-3 airplanes provides an equivalent level of safety to the repetitive inspections required by AD 90-12-08. The actions specified by this AD are intended to prevent failure of the tailplane structure caused by cracked tailplane main rib forward flanges or main rib forwardlower flanges at the tailplane front attachment fitting, which, if not detected and corrected, could result in loss of control of the airplane.

Final rule

96-09-04 DE HAVILLAND: Amendment 39-9578. Docket No. 95-CE-47-AD; Supersedes AD 90-12-08, Amendment 39-6622.

Applicability: Model DHC-3 airplanes (all serial numbers), certificated in any category, that do not have Modification 3/935 incorporated in accordance with de Havilland Service Bulletin (SB) number (No.) 3/50, Revision A, dated February 17, 1995.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Within the next 3 calendar months after the effective date of this AD, unless already accomplished (compliance with AD 90-12-08), and thereafter at intervals not to exceed 24 calendar months.

To prevent failure of the tailplane structure caused by cracked tailplane main rib forward flanges or main rib forward lower flanges at the tailplane front attachment fitting, which, if not detected and corrected, could result in loss of control of the airplane, accomplish the following:

(a) Inspect, using dye penetrant methods, the tailplane main rib forward flanges and the main rib forward lower flanges at the tailplane front attachment fitting in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB No. 3/46, Revision B, dated December 1, 1989.

NOTE 2: Pay particular attention to the front attachment fitting area.

(b) Prior to further flight, repair any tailplane main rib forward flange or main rib forward lower flange found cracked during any inspection required by this AD. Accomplish this repair in accordance with the ACCOMPLISHMENT INSTRUCTIONS section of de Havilland SB No. 3/46, Revision B, dated December 1, 1989.

(c) Installing tailplane root rib angles and plates of improved design (Modification 3/935) in accordance with de Havilland SB 3/50, Revision A, dated February 17, 1995, terminates the repetitive inspection requirement of this AD. Modification 3/935 may be incorporated at any time provided that any tailplane main rib forward flange or main rib forward lower flange found cracked during any inspection required by this AD is repaired.

(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(e) An alternative method of compliance or adjustment of the initial or repetitive compliance times that provides an equivalent level of safety may be approved by the Manager, New York Aircraft Certification Office, 10 5th St., 3rd Floor, Valley Stream, New York 11581. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, New York Aircraft Certification Office.

NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York Aircraft Certification Office.

(f) Alternative methods of compliance approved in accordance with AD 90-12-08 (superseded by this action) are considered approved as alternative methods of compliance with this AD.

(g) The inspections, repairs, and replacements required by this AD shall be done in accordance with de Havilland Service Bulletin No. 3/46, Revision B, dated December 1, 1989, and de Havilland Service Bulletin No. 3/50, Revision A, dated February 17, 1995. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Bombardier Inc. (the parent company of de Havilland), Bombardier Regional Aircraft Division, Garrett Boulevard, Downsview, Ontario, Canada M3K 1Y5; telephone (416) 633-7310. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW., 7th Floor, suite 700, Washington, DC.

(h) This amendment (39-9578) supersedes AD 90-12-08, Amendment 39-6622.

(i) This amendment becomes effective on May 17, 1996.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to de Havilland Model DHC-3 airplanes was published in the Federal Register on November 14, 1995 (60 FR 57201). This action would retain the repetitive inspections currently required by AD 90-12-08, and would allow incorporating a certain modification as terminating action for these repetitive inspections. Accomplishment of this action will be in accordance with de Havilland Service Bulletin (SB) No. 3/46, Revision B, dated December 1, 1989 and de Havilland SB No. 3/50, Revision A, dated February 17, 1995.

Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposed rule or the FAA's determination of the cost to the public.

After careful review of all available information related to the subject presented above, the FAA has determined that air safety andthe public interest require the adoption of the rule as proposed except for minor editorial corrections. The FAA has determined that these minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

The FAA estimates that 49 airplanes in the U.S. registry will be affected by this AD, that it will take approximately 35 workhours per airplane to accomplish the inspection and that the average labor rate is approximately $60 an hour. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $102,900 or $2,100 per airplane. This figure represents the cost of the initial inspection, and does not reflect the costs for repetitive inspections or possible repairs. The FAA has no way of determining how many tailplane main rib forward or main rib forward lower flanges may need to be repaired or how many repetitive inspections each owner/operator of the affected airplanes wouldincur over the life of the airplane.

The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the final evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption "ADDRESSES".

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 USC 106(g), 40113, 44701.

Section 39.13 - [AMENDED]
2. Section 39.13 is amended by removing AD 90-12-08, Amendment 39-6622, and by adding a new airworthiness directive (AD) to read as follows: